Small electronic circuits are often used in conjunction with high-frequency signals. However, some transmission materials used in these circuits cause significant signal loss when carrying high frequency signals. For example, signals transmitted at 3 to 4 GHz over a small portion of FR4 substrate may experience 30 to 40 dB of signal loss.
Circuit designers attempt to compensate for this loss by filtering received signals. In one example, received signals are converted to digital signals with an analog-to digital converter and then filtered using a digital filter. Analog-to-digital converters are, however, often costly and difficult to implement at high data rates. Even if analog-to-digital conversion is not problematic for a given high-frequency application, subsequent filtering of the digital high-frequency signals may itself be difficult to design and/or implement.
Analog filters may be used to address the foregoing, but power requirements of these filters usually increase with signal frequency. For example, conventional Finite Impulse Response (FIR) analog filters operate by convolving samples of a received signal with a set of weighting coefficients. A finite state machine typically performs the convolution by rotating the coefficients amongst a set of multipliers for multiplying a fixed signal sample by a weighting coefficient and/or by rotating the signal samples amongst a set of multipliers for multiplying a signal sample by a fixed weighting coefficient. The finite state machine as well as other elements used to perform the convolution adds significantly to the power requirements of the FIR filter, particularly during high-frequency operation.